A variable depth mid-deep ground source heat pump system

Abstract

The present invention discloses a variable depth medium-deep geothermal heat pump system, the ground source side of which is a first buried pipe and a second buried pipe both of which are U-shaped, and also includes a first pipeline unit, a second pipeline unit, and a first horizontal pipe and a second horizontal pipe both buried underground. The purpose of the present invention is to provide a variable depth medium-deep geothermal heat pump system, which can realize the cooling function in summer while meeting the heating demand in winter, improve the utilization rate of heat pump equipment, and set the system control valve in the above-ground machine room or in the inspection well, which is convenient for the operation control and daily maintenance of the geothermal heat pump system; at the same time, it realizes deep heat extraction in winter and middle-layer heat discharge in summer, and improves the heat exchange efficiency between soil and heat medium.

Description

Technical Field

[0001] The present invention relates to the field of ground source heat pump systems, and more specifically to a variable depth mid-deep ground source heat pump system. Background Art

[0002] At present, there are certain problems in the use of mid-deep geothermal heat. The deeper the soil, the higher its temperature. High soil temperature is conducive to heat extraction in winter, and low soil temperature is conducive to heat discharge in summer. Conventional ground source heat pump systems usually use the same depth and often cannot achieve both. The specific analysis of mid-deep soil heat exchange is as follows:

[0003] (1) When the effective heat exchange depth of the buried pipe is in the middle layer: In winter, due to the low soil temperature, the heat exchange efficiency of the ground source heat pump system is reduced, affecting the operating energy efficiency of the ground source heat pump system; in summer, there is a large temperature gradient between the cooling water temperature of the ground source heat pump system and the soil temperature, which is conducive to heat dissipation to the soil.

[0004] (2) When the effective heat exchange depth of the buried pipe is deep: In winter, due to the high soil temperature, the heat exchange efficiency of the ground source heat pump system is improved; in summer, the temperature difference between the cooling water of the ground source heat pump and the ground temperature is only small or even lower than the ground temperature, making it difficult to discharge heat to the soil.

[0005] At present, the heat exchange holes of general medium and deep ground source heat pump systems on the market all adopt single well circulation or U-shaped buried pipe forms. Both forms use a single deep soil source as a low-temperature heat source. According to the soil temperature distribution, it can be seen that under the influence of the earth's heat flow, the soil temperature at a depth of more than 20 meters usually increases with the increase of depth, and remains unchanged throughout the year and is not affected by the surface environment.

[0006] For the existing conventional medium-deep buried pipes, since the soil temperature increases significantly with the increase of depth, from the perspective of heat exchange, the higher the soil temperature, the more conducive it is for the buried pipe system to obtain heat in winter, but it will also reduce the heat dissipation capacity in summer. The circulating working fluid of the ground source heat pump system in summer is 25 / 30℃. When the soil depth reaches 600m, the soil temperature is close to 25℃. At this time, the temperature difference between the cooling water temperature on the ground source side of the ground source heat pump system and the soil temperature is only small or even lower than the ground temperature, making it difficult to dissipate heat to the soil, causing the system to lose its summer cooling capacity. Therefore, conventional medium-deep ground source heat pump systems can usually only provide winter heating functions and cannot meet summer cooling needs. Summary of the invention

[0007] The purpose of the present invention is to provide a variable-depth mid-deep geothermal heat pump system, which is based on conventional double-U buried pipes and realizes variable-depth operation under different working conditions by setting a mid-layer bypass branch and a switching valve. It can simultaneously realize heat extraction from the deep soil layer and heat discharge from the middle layer, which can not only meet the heating needs in winter, but also realize the cooling function in summer, thereby improving the utilization efficiency of geothermal energy.

[0008] In order to achieve these purposes and other advantages according to the present invention, a variable-depth medium-deep ground source heat pump system is provided, wherein the ground source side is a first buried pipe and a second buried pipe, both of which are U-shaped, the first buried pipe and the second buried pipe are both buried underground, the heat pump has a first heat exchanger and a second heat exchanger, and the water medium inlet and outlet ports of the second heat exchanger are respectively connected to the water outlet of the second buried pipe and the water inlet of the first buried pipe, and also includes a first pipeline unit, a second pipeline unit and a first horizontal pipe and a second horizontal pipe both buried underground, the water inlet pipe of the first buried pipe and the water inlet pipe of the second buried pipe are connected through the first horizontal pipe, the water outlet pipe of the first buried pipe and the water outlet pipe of the second buried pipe are connected through the second horizontal pipe, the first pipeline unit is respectively connected to the inlet and outlet of the compressor of the heat pump, and the two ends of the expansion valve of the heat pump are respectively The circulating working fluid channel of the first heat exchanger and the circulating working fluid channel of the second heat exchanger of the heat pump are connected with the first pipeline unit. The first pipeline unit selectively connects the outlet and the inlet of the compressor of the heat pump with the circulating working fluid channel of the first heat exchanger and the circulating working fluid channel of the second heat exchanger respectively, or connects the outlet and the inlet of the compressor with the circulating working fluid channel of the second heat exchanger and the circulating working fluid channel of the first heat exchanger respectively. The water inlet and the water outlet of the first buried pipe and the second buried pipe are both connected to the second pipeline unit. The second pipeline unit selectively connects the water inlet of the first buried pipe with the water inlet of the second buried pipe and the water outlet of the first buried pipe with the water outlet of the second buried pipe, or connects the water inlet and the water outlet of the first buried pipe and the water inlet and the water outlet of the second buried pipe.

[0009] Preferably, in the variable-depth medium-deep geothermal heat pump system, the first pipeline unit is a first four-way reversing valve, the inlet and outlet of the heat pump compressor are respectively connected to the first four-way reversing valve, and the two ends of the heat pump expansion valve are respectively connected to the first heat exchanger and the second heat exchanger of the heat pump and the first four-way reversing valve, and the first four-way reversing valve selectively connects the outlet and inlet of the heat pump compressor to the first heat exchanger and the second heat exchanger respectively, or connects the outlet and inlet of the compressor to the second heat exchanger and the first heat exchanger respectively.

[0010] Preferably, in the variable-depth medium-deep ground source heat pump system, the second pipeline unit includes a first pipeline and a second pipeline both of which are horizontally arranged, the two ends of the first pipeline are respectively connected to the water inlet of the first buried pipe and the water outlet of the second buried pipe, and at the same time, the water outlet of the first buried pipe and the water inlet of the second buried pipe are both connected to the first pipeline, the two ends of the second pipeline are respectively connected to the water inlet pipe of the first buried pipe and the water inlet pipe of the second buried pipe, a first valve is provided on the part of the first pipeline located between the water outlet of the first buried pipe and the water inlet of the second buried pipe, a second valve is provided on the second pipeline, a third valve is provided on the part of the water inlet pipe of the second buried pipe located between the first pipeline and the second pipeline, and a fourth valve is provided on the part of the first pipeline located between the water inlet and the water outlet of the first buried pipe.

[0011] Preferably, in the variable-depth medium-deep geothermal heat pump system, the second pipeline unit is a second four-way reversing valve, the water inlet and the water outlet of the first buried pipe and the second buried pipe are both connected to the second four-way reversing valve, and the second four-way reversing valve selectively connects the water inlet of the first buried pipe with the water inlet of the second buried pipe and the water outlet of the first buried pipe with the water outlet of the second buried pipe, or connects the water inlet and the water outlet of the first buried pipe and the water inlet and the water outlet of the second buried pipe.

[0012] The present invention also provides a winter heating method of a variable depth medium-deep geothermal heat pump system, which uses the variable depth medium-deep geothermal heat pump system and includes the following steps:

[0013] Adjusting the first four-way reversing valve so that the outlet and the inlet of the compressor are connected to the first heat exchanger and the second heat exchanger respectively;

[0014] Open the first valve and the second valve, and close the third valve and the fourth valve, so that the water inlet of the first buried pipe is connected to the water inlet of the second buried pipe and the water outlet of the first buried pipe is connected to the water outlet of the second buried pipe.

[0015] The present invention also provides a summer cooling method of a variable depth medium-deep geothermal heat pump system, which uses the variable depth medium-deep geothermal heat pump system and includes the following steps:

[0016] Adjusting the first four-way reversing valve so that the outlet and the inlet of the compressor are connected to the second heat exchanger and the first heat exchanger respectively;

[0017] The third valve and the fourth valve are opened, and the first valve and the second valve are closed, so that the water inlet and the water outlet of the first buried pipe are connected and the water inlet and the water outlet of the second buried pipe are connected.

[0018] The present invention also provides a winter heating method of a variable depth medium-deep geothermal heat pump system, which uses the variable depth medium-deep geothermal heat pump system and includes the following steps:

[0019] Adjusting the first four-way reversing valve so that the outlet and the inlet of the compressor are connected to the first heat exchanger and the second heat exchanger respectively;

[0020] The second four-way reversing valve is adjusted to allow the water inlet of the first buried pipe to communicate with the water inlet of the second buried pipe and the water outlet of the first buried pipe to communicate with the water outlet of the second buried pipe.

[0021] The present invention also provides a summer cooling method of a variable depth medium-deep geothermal heat pump system, which uses the variable depth medium-deep geothermal heat pump system and includes the following steps:

[0022] Adjusting the first four-way reversing valve so that the outlet and the inlet of the compressor are connected to the second heat exchanger and the first heat exchanger respectively;

[0023] The second four-way reversing valve is adjusted to connect the water inlet and the water outlet of the first buried pipe and the water inlet and the water outlet of the second buried pipe.

[0024] The beneficial effects of the present invention are:

[0025] (1) While meeting the winter heating demand, it also realizes the summer cooling function, thereby improving the utilization rate of heat pump equipment.

[0026] (2) The system control valve is installed in the above-ground machine room or inspection well to facilitate the operation, regulation and daily maintenance of the ground source heat pump system.

[0027] (3) It achieves deep heat extraction in winter and middle heat discharge in summer, thus improving the heat exchange efficiency between soil and heat medium.

[0028] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of the heat exchange holes of the variable depth mid-deep ground source heat pump system of the present invention;

[0030] Figure 2 It is a structural schematic diagram of a ground source heat pump system described in one embodiment of the present invention;

[0031] Figure 3 It is a structural schematic diagram of a ground source heat pump system described in another embodiment of the present invention;

[0032] Figure 4 It is a structural schematic diagram of a ground source heat pump system described in another embodiment of the present invention;

[0033] Figure 5 It is a structural schematic diagram of a ground source heat pump system described in another embodiment of the present invention.

[0034] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0035] 1. First buried pipe; 2. Second buried pipe; 3. Second heat exchanger; 4. First horizontal pipe; 5. Second horizontal pipe; 6. Compressor; 7. First heat exchanger; 8. First four-way reversing valve; 9. First pipeline; 10. Second pipeline; 11. Second four-way reversing valve; 12. Expansion valve. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0037] It should be noted that, in the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientation or position relationships, are based on the orientation or position relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0038] like Figure 1As shown, an embodiment of the present invention provides a variable-depth medium-deep ground source heat pump system, wherein the ground source side is a first buried pipe 1 and a second buried pipe 2, both of which are U-shaped, the first buried pipe 1 and the second buried pipe 2 are both buried underground, the water medium inlet and outlet ports of the second heat exchanger 3 of the heat pump are respectively connected to the water outlet of the second buried pipe 2 and the water inlet of the first buried pipe 1, and also includes a first pipeline 9 unit, a second pipeline unit and a first horizontal pipe 4 and a second horizontal pipe 5, both of which are buried underground, the water inlet pipe of the first buried pipe 1 and the water inlet pipe of the second buried pipe 2 are connected through the first horizontal pipe 4, the water outlet pipe of the first buried pipe 1 and the water outlet pipe of the second buried pipe 2 are connected through the second horizontal pipe 5, and the height of the first horizontal pipe 4 is higher than the height of the second horizontal pipe 5, the first pipeline 9 unit is respectively connected to the inlet and outlet of the compressor 6 of the heat pump, and both ends of the expansion valve 12 of the heat pump The circulating working fluid channel of the first heat exchanger 7 and the circulating working fluid channel of the second heat exchanger 3 of the heat pump are respectively connected with the first pipeline 9 unit. The first pipeline 9 unit selectively connects the outlet and the inlet of the compressor 6 of the heat pump with the circulating working fluid channel of the first heat exchanger 7 and the circulating working fluid channel of the second heat exchanger 3 respectively, or connects the outlet and the inlet of the compressor 6 with the circulating working fluid channel of the second heat exchanger 3 and the circulating working fluid channel of the first heat exchanger 7 respectively. The water inlet and the water outlet of the first buried pipe 1 and the second buried pipe 2 are both connected to the second pipeline unit. The second pipeline unit selectively connects the water inlet of the first buried pipe 1 and the water inlet of the second buried pipe 2 and the water outlet of the first buried pipe 1 and the water outlet of the second buried pipe 2, or connects the water inlet and the water outlet of the first buried pipe 1 and the water inlet and the water outlet of the second buried pipe 2.

[0039] In this embodiment, the variable depth mid-deep geothermal heat pump system is based on conventional double U-type buried pipes, that is, the ground source side is a first buried pipe 1 and a second buried pipe 2, both of which are U-shaped, and the first buried pipe 1 and the second buried pipe 2 are buried underground. The first heat exchanger 7 and the second heat exchanger 3 of the heat pump are respectively arranged on the load side and the buried side. The first heat exchanger 7 and the second heat exchanger 3 here adopt the existing technology, and the two have the same structure and have two circulation channels. Cold and hot water flow through the two circulation channels respectively, and heat exchange can be carried out in the first heat exchanger 7 or the second heat exchanger 3. In this embodiment, variable depth operation under different working conditions can be achieved by setting a middle-layer bypass branch and a switching valve, and heat extraction from the deep soil layer and heat discharge from the middle layer can be achieved at the same time, which can meet the heating demand in winter and realize the cooling function in summer, thereby improving the utilization efficiency of geothermal energy.

[0040] Preferably, as another embodiment of the present invention, Figure 1 Based on the embodiment shown, it also includes:

[0041] like Figure 2-Figure 5As shown, the first pipeline 9 unit is a first four-way reversing valve 8, the inlet and outlet of the heat pump compressor 6 are respectively connected to the first four-way reversing valve 8, and the two ends of the heat pump expansion valve 12 are respectively connected to the first heat exchanger 7 and the second heat exchanger 3 of the heat pump and the first four-way reversing valve 8. The first four-way reversing valve 8 selectively connects the outlet and inlet of the heat pump compressor 6 to the first heat exchanger 7 and the second heat exchanger 3, or connects the outlet and inlet of the compressor 6 to the second heat exchanger 3 and the first heat exchanger 7.

[0042] In this embodiment, if Figure 2-Figure 5 As shown, the first four-way reversing valve 8 has four connectors 1a, 1b, 1c and 1d, which are respectively connected to the second heat exchanger 3, the water outlet of the compressor 6, the first heat exchanger 7 and the water inlet of the compressor 6. When 1a and 1d are connected, and 1b and 1c are connected, the outlet and inlet of the compressor 6 of the heat pump can be connected to the first heat exchanger 7 and the second heat exchanger 3 respectively; when 1a and 1b are connected, and 1d and 1c are connected, the outlet and inlet of the compressor 6 can be connected to the second heat exchanger 3 and the first heat exchanger 7 respectively.

[0043] Preferably, as another embodiment of the present invention, Figure 1 Based on the embodiment shown, it also includes:

[0044] like Figure 2-Figure 4 As shown, the second pipeline unit includes a first pipeline 9 and a second pipeline 10, both of which are horizontally arranged, and the two ends of the first pipeline 9 are respectively connected to the water inlet of the first buried pipe 1 and the water outlet of the second buried pipe 2, and at the same time, the water outlet of the first buried pipe 1 and the water inlet of the second buried pipe 2 are both connected to the first pipeline 9. The second pipeline 10 is arranged below the first pipeline 9, and its two ends are respectively connected to the water inlet pipe of the first buried pipe 1 and the water inlet pipe of the second buried pipe 2, a first valve is provided on the part of the first pipeline 9 located between the water outlet of the first buried pipe 1 and the water inlet of the second buried pipe 2, a second valve is provided on the second pipeline 10, a third valve is provided on the part of the water inlet pipe of the second buried pipe 2 located between the first pipeline 9 and the second pipeline 10, and a fourth valve is provided on the part of the first pipeline 9 located between the water inlet and the water outlet of the first buried pipe 1.

[0045] In this embodiment, the first valve and the second valve are opened, and the third valve and the fourth valve are closed at the same time. At this time, the water inlet of the first buried pipe 1 is connected to the water inlet of the second buried pipe 2, and both are connected to the second heat exchanger 3. At the same time, the water outlet of the first buried pipe 1 is connected to the water outlet of the second buried pipe 2, and both are connected to the second heat exchanger 3. At this time, the second heat exchanger 3 and the first buried pipe 1 and the second buried pipe 2 form a passage. Specifically:

[0046] like Figure 2 As shown, during winter heating, the first four-way reversing valve 8 is adjusted so that the outlet and inlet of the compressor 6 are connected to the first heat exchanger 7 and the second heat exchanger 3 respectively; the first valve and the second valve are opened, and the third valve and the fourth valve are closed, so that the water inlet of the first buried pipe 1 is connected to the water inlet of the second buried pipe 2, and the water outlet of the first buried pipe 1 is connected to the water outlet of the second buried pipe 2. According to the principle of static pressure of fluid, driven by the internal water pressure, the pressure of node N2 is equal to the pressure of node N4, and the pressure of node N1 is equal to the pressure of node N3, so (P N2 =P N4 )>(P N1 =P N3 ), driven by the pressure difference, the working fluid flows from node N4 to node N3, and from node N2 to node N1, so it will enter the deep soil layer to extract heat, improve the heat exchange efficiency between the working fluid and the soil, and meet the heating demand.

[0047] like Figure 3 As shown, in summer cooling, the first four-way reversing valve 8 is adjusted so that the outlet and inlet of the compressor 6 are connected to the second heat exchanger 3 and the first heat exchanger 7 respectively; the third valve and the fourth valve are opened, and the first valve and the second valve are closed, so that the water inlet and the water outlet of the first buried pipe 1 are connected and the water inlet and the water outlet of the second buried pipe 2 are connected. By using the static pressure principle of fluid, driven by the internal water pressure, the pressure of the node N3 is equal to the pressure of the node N4, and the pressure of the node N1 is equal to the pressure of the node N2, so P N3 =P N4 >P N1 =P N2 Driven by the pressure difference, the working fluid flows from node N4 to node N2 and from node N3 to node N1, so it will enter the middle layer of the soil to dissipate heat, ensuring the heat exchange temperature difference between the cooling water temperature and the soil temperature of the ground source heat pump system, thereby achieving effective heat dissipation and meeting the cooling demand.

[0048] Preferably, as another embodiment of the present invention, Figure 1 Based on the embodiment shown, it also includes:

[0049] like Figure 4-Figure 5 As shown, the second pipeline unit is a second four-way reversing valve 11, and the water inlet and the water outlet of the first buried pipe 1 and the second buried pipe 2 are both connected to the second four-way reversing valve 11. The second four-way reversing valve 11 selectively connects the water inlet of the first buried pipe 1 with the water inlet of the second buried pipe 2 and the water outlet of the first buried pipe 1 with the water outlet of the second buried pipe 2, or connects the water inlet and the water outlet of the first buried pipe 1 and the water inlet and the water outlet of the second buried pipe 2.

[0050] In this embodiment, the second pipeline unit is a second four-way reversing valve 11. Figure 4 As shown, the second four-way reversing valve 11 has four joints 2a, 2b, 2c and 2d, which respectively connect the four joints 2a, 2b, 2c and 2d with the water outlet of the second buried pipe 2, the water outlet of the first buried pipe 1, the water inlet of the first buried pipe 1 and the water inlet of the second buried pipe 2, so that when 2a and 2b are connected and 2c and 2d are connected, the water inlet of the first buried pipe 1 and the water inlet of the second buried pipe 2 are connected, and the water outlet of the first buried pipe 1 and the water outlet of the second buried pipe 2 are connected; when 2a and 2d are connected and 2c and 2b are connected, the water inlet and water outlet of the first buried pipe 1 and the water inlet and water outlet of the second buried pipe 2 are connected.

[0051] like Figure 4 As shown, during winter heating, the first four-way reversing valve 8 is adjusted so that the outlet and the inlet of the compressor 6 are connected to the first heat exchanger 7 and the second heat exchanger 3 respectively; the second four-way reversing valve 11 is adjusted so that the water inlet of the first buried pipe 1 is connected to the water inlet of the second buried pipe 2, and the water outlet of the first buried pipe 1 is connected to the water outlet of the second buried pipe 2. According to the principle of static pressure of fluid, driven by the internal water pressure, the pressure of the node N2 is equal to the pressure of the node N4, and the pressure of the node N1 is equal to the pressure of the node N3, so (P N2 =P N4 )>(P N1 =P N3 ), driven by the pressure difference, the working fluid flows from node N4 to node N3, and from node N2 to node N1, so it will enter the deep soil layer to extract heat, improve the heat exchange efficiency between the working fluid and the soil, and meet the heating demand.

[0052] like Figure 5 As shown, in summer cooling, the first four-way reversing valve 8 is adjusted so that the outlet and inlet of the compressor 6 are connected to the second heat exchanger 3 and the first heat exchanger 7 respectively; the second four-way reversing valve 11 is adjusted so that the water inlet and the water outlet of the first buried pipe 1 are connected and the water inlet and the water outlet of the second buried pipe 2 are connected. By using the static pressure principle of fluid, driven by the internal water pressure, the pressure of the node N3 is equal to the pressure of the node N4, and the pressure of the node N1 is equal to the pressure of the node N2, so P N3 =P N4 >P N1 =P N2 Driven by the pressure difference, the working fluid flows from node N4 to node N2 and from node N3 to node N1, so it will enter the middle layer of the soil to dissipate heat, ensuring the heat exchange temperature difference between the cooling water temperature and the soil temperature of the ground source heat pump system, thereby achieving effective heat dissipation and meeting the cooling demand.

[0053] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A variable depth medium-deep ground source heat pump system, wherein the ground source side is a first buried pipe (1) and a second buried pipe (2) both of which are U-shaped, the first buried pipe (1) and the second buried pipe (2) are both buried underground, the heat pump has a first heat exchanger (7) and a second heat exchanger (3), and the water medium inlet and outlet ports of the second heat exchanger (3) are respectively connected to the water outlet of the second buried pipe (2) and the water inlet of the first buried pipe (1), characterized in that: The heat pump further comprises a first pipeline unit, a second pipeline unit, and a first horizontal pipe (4) and a second horizontal pipe (5) all of which are buried underground. The water inlet pipe of the first buried pipe (1) and the water inlet pipe of the second buried pipe (2) are connected via the first horizontal pipe (4), and the water outlet pipe of the first buried pipe (1) and the water outlet pipe of the second buried pipe (2) are connected via the second horizontal pipe (5). The first pipeline unit is respectively connected to the inlet and outlet of the compressor (6) of the heat pump. Both ends of the expansion valve of the heat pump are respectively connected to the first pipeline unit via the circulating working fluid channel of the first heat exchanger (7) of the heat pump and the circulating working fluid channel of the second heat exchanger (3). The first pipeline unit selectively connects the outlet and inlet of the compressor (6) of the heat pump to the first horizontal pipe (5). The circulating working medium channel of a heat exchanger (7) is connected to the circulating working medium channel of a second heat exchanger (3), or the outlet and inlet of the compressor (6) are connected to the circulating working medium channel of the second heat exchanger (3) and the circulating working medium channel of the first heat exchanger (7) respectively; the water inlet and the water outlet of the first buried pipe (1) and the second buried pipe (2) are both connected to the second pipeline unit; the second pipeline unit selectively connects the water inlet of the first buried pipe (1) with the water inlet of the second buried pipe (2) and the water outlet of the first buried pipe (1) with the water outlet of the second buried pipe (2), or connects the water inlet and the water outlet of the first buried pipe (1) and the water inlet and the water outlet of the second buried pipe (2); The first pipeline unit is a first four-way reversing valve (8), the inlet and outlet of the compressor (6) of the heat pump are respectively connected to the first four-way reversing valve (8), and both ends of the expansion valve (12) of the heat pump are respectively connected to the first four-way reversing valve (8) through the first heat exchanger (7) and the second heat exchanger (3) of the heat pump, and the first four-way reversing valve (8) selectively connects the outlet and inlet of the compressor (6) of the heat pump to the first heat exchanger (7) and the second heat exchanger (3), or connects the outlet and inlet of the compressor (6) to the second heat exchanger (3) and the first heat exchanger (7); The second pipeline unit comprises a first pipeline (9) and a second pipeline (10) both of which are arranged horizontally, the two ends of the first pipeline (9) are respectively connected to the water inlet of the first buried pipe (1) and the water outlet of the second buried pipe (2), and the water outlet of the first buried pipe (1) and the water inlet of the second buried pipe (2) are both connected to the first pipeline (9), the two ends of the second pipeline (10) are respectively connected to the water inlet pipe of the first buried pipe (1) and the water inlet pipe of the second buried pipe (2), the first pipeline (9) is provided with a first valve on the part between the water outlet of the first buried pipe (1) and the water inlet of the second buried pipe (2), the second pipeline (10) is provided with a second valve, the water inlet pipe of the second buried pipe (2) is provided with a third valve on the part between the first pipeline (9) and the second pipeline (10), and the first pipeline (9) is provided with a fourth valve on the part between the water inlet and the water outlet of the first buried pipe (1); The second pipeline unit is a second four-way reversing valve (11); the water inlet and the water outlet of the first buried pipe (1) and the second buried pipe (2) are both connected to the second four-way reversing valve (11); the second four-way reversing valve (11) selectively connects the water inlet of the first buried pipe (1) with the water inlet of the second buried pipe (2) and the water outlet of the first buried pipe (1) with the water outlet of the second buried pipe (2), or connects the water inlet and the water outlet of the first buried pipe (1) and the water inlet and the water outlet of the second buried pipe (2).

2. A winter heating method of a variable depth medium-deep geothermal heat pump system, using the variable depth medium-deep geothermal heat pump system as claimed in claim 1, characterized in that: The following steps are involved: adjusting the first four-way reversing valve (8) so that the outlet and the inlet of the compressor (6) are connected to the first heat exchanger (7) and the second heat exchanger (3) respectively; The first valve and the second valve are opened, and the third valve and the fourth valve are closed, so that the water inlet of the first buried pipe (1) is connected to the water inlet of the second buried pipe (2), and the water outlet of the first buried pipe (1) is connected to the water outlet of the second buried pipe (2).

3. A summer cooling method of a variable depth medium-deep geothermal heat pump system, using the variable depth medium-deep geothermal heat pump system as claimed in claim 1, characterized in that: The following steps are involved: adjusting the first four-way reversing valve (8) so that the outlet and the inlet of the compressor (6) are connected to the second heat exchanger (3) and the first heat exchanger (7) respectively; The third valve and the fourth valve are opened, and the first valve and the second valve are closed, so that the water inlet and the water outlet of the first buried pipe (1) are connected and the water inlet and the water outlet of the second buried pipe (2) are connected.

4. A winter heating method of a variable depth mid-deep geothermal heat pump system, using the variable depth mid-deep geothermal heat pump system as claimed in claim 1, characterized in that: The following steps are involved: adjusting the first four-way reversing valve (8) so that the outlet and the inlet of the compressor (6) are connected to the first heat exchanger (7) and the second heat exchanger (3) respectively; The second four-way reversing valve (11) is adjusted so that the water inlet of the first buried pipe (1) is connected to the water inlet of the second buried pipe (2), and the water outlet of the first buried pipe (1) is connected to the water outlet of the second buried pipe (2).

5. A summer cooling method of a variable depth mid-deep geothermal heat pump system, using the variable depth mid-deep geothermal heat pump system as claimed in claim 1, characterized in that: The following steps are involved: adjusting the first four-way reversing valve (8) so that the outlet and the inlet of the compressor (6) are connected to the second heat exchanger (3) and the first heat exchanger (7) respectively; The second four-way reversing valve (11) is adjusted so that the water inlet and the water outlet of the first buried pipe (1) are connected and the water inlet and the water outlet of the second buried pipe (2) are connected.

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